Add Fields

The Add Fields processor sets attributes, resource fields, and log record body fields on telemetry in a pipeline. Each field can be inserted only when absent, updated only when present, or upserted (inserted or updated). An optional OTTL condition limits the processor to matching records. It operates on logs, metrics, and traces, though body fields apply to logs only.

Supported Telemetry Types

Metrics	Logs	Traces
✓	✓	✓

Configuration

When to apply

Parameter	Type	Required	Default	Description
Choose Telemetry Type	Telemetry Selector	Yes	Logs, Metrics, Traces	The signals this instance runs on. Fields are only applied to the selected telemetry types.
Condition	OTTL Condition	No	(empty)	An OTTL condition that must evaluate to true for a field to be applied. When empty, the processor applies to all telemetry.

Fields

The Fields parameter is a repeatable list. Each row adds or modifies one field.

Parameter	Type	Required	Default	Description
Field Type	Enum: Attributes, Resource, Body	Yes	Attributes	The context the field is written to. Body is logs-only; Body rows are ignored for metrics and traces.
Action	Enum: Insert, Update, Upsert	Yes	Upsert	Insert adds the field only if it does not already exist. Update changes the value only if the field already exists. Upsert inserts or updates.
Key	String	Yes	—	The field name to add or modify. Use bracket notation for nested keys (for example attributes["k8s.pod.name"]).
Value	String	Yes	—	The value associated with the key.

Examples

Tag metrics with environment and region

Append static resource fields so metrics can be filtered by where they originated. This Fields list has three rows, covering Resource/Upsert, Resource/Insert, and Attributes/Update:

- type: add_fields_v2
  parameters:
    - name: telemetry_types
      value:
        - Metrics
    - name: fields
      value:
        - field_type: resource
          action: upsert
          field: environment
          value: production
        - field_type: resource
          action: insert
          field: region
          value: us-east1
        - field_type: attributes
          action: update
          field: pipeline.stage
          value: ingest

Add a resource field to error logs only

This example uses an OTTL condition so the field is added only to logs whose body level is error. Given a log body like:

{
  "level": "error",
  "message": "failed to authenticate user: test",
  "timestamp": "2023-07-05T13:40:17.549-0400"
}

Configure the condition and a single field:

- type: add_fields_v2
  parameters:
    - name: telemetry_types
      value:
        - Logs
    - name: condition
      value: body["level"] == "error"
    - name: fields
      value:
        - field_type: attributes
          action: upsert
          field: application_name
          value: auth-service

Internally the processor renders an OTTL set statement against the transform processor, for example set(attributes["application_name"], "auth-service") where body["level"] == "error".

Configuration Tips

• Action semantics matter: Insert will not overwrite an existing value, Update will not create a missing field, and Upsert always writes. Pick the one that matches whether the field may already be present.
• Body fields are applied only to logs. If a Body row is configured while Metrics or Traces is selected, that row is silently skipped for those signals.
• One instance can target multiple signals at once, but the Fields list is shared across them. Use separate instances when logs need body fields that metrics and traces should not receive.

Troubleshooting

A field is not being added

Symptoms: telemetry passes through unchanged after the processor runs.

Solutions:

1. Check the Action. Insert is skipped when the key already exists, and Update is skipped when the key is absent. Switch to Upsert to write unconditionally.
2. Confirm the Condition evaluates to true for the records you expect. An over-specific condition (or a quoting mistake, such as == error instead of == "error") drops every record.

A body field never appears on metrics or traces

Symptoms: a Body-type row works for logs but has no effect on metrics or traces.

Solutions:

1. Body fields apply to logs only. Use Attributes or Resource for metrics and traces, or split the configuration into separate instances per signal.

Standalone Processor

apiVersion: bindplane.observiq.com/v1
kind: Processor
metadata:
  name: add-fields
spec:
  type: add_fields_v2
  parameters:
    - name: telemetry_types
      value:
        - Logs
        - Metrics
        - Traces
    - name: condition
      value: ""
    - name: fields
      value:
        - field_type: resource
          action: upsert
          field: environment
          value: production
        - field_type: resource
          action: insert
          field: region
          value: us-east1
        - field_type: attributes
          action: update
          field: pipeline.stage
          value: ingest

Related Resources

• Transform Processor — OpenTelemetry Collector Contrib
• Delete Fields
• Rename Fields